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Evolution

Evolution. Chapters 14-17 p261. Biogenesis – “life” “creation”. All living things come from other living things. History. Spontaneous Generation Living things could arise from non-living things Francesco Redi Jars with Meat One open, one with netting Found maggots on open one

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Evolution

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  1. Evolution Chapters 14-17 p261

  2. Biogenesis – “life” “creation” • All living things come from other living things

  3. History • Spontaneous Generation Living things could arise from non-living things • Francesco Redi • Jars with Meat • One open, one with netting • Found maggots on open one If spontaneous Generation was TRUE, there should have been maggots on both. • New Spontaneous Generation: only simple things come from non-living things

  4. History • LazzaroSpallanzani • Boiled Broth, Sealed it • Found NO life If New Sponanteous Generation was true, there should have been bacteria or mold in the broth. • Critics said he killed the ‘vital force’ in the air so life couldn’t start • Vital Force – something in the air that made simple life

  5. History • Louis Pastuer • Made a special curved flask that would let in ‘vital force’ but not germs • Found NO life • Broke flask, then it spoiled. FINALLY DISPROVED Spontaneous Generation!

  6. So if all living things come from other living things, where did the first living thing come from? • All religions try to explain this in their own way

  7. History of Earth • Earth is about 4.6 billion years old (4,600,000,000) • Life about 3.5 billion years old (3,500,000,000) How do we know? • Radioactive Dating: • Studying the chemical make up of an object to determine its age. Before we can understand how to date something we need to get radioactivity

  8. (How do we know how old Earth is?)Radioactivity • (The over stuffed closet) • Something is radioactive if it has too much energy or particles stored in one place. • It decays when it spontaneously releases the extra. • Often changing an atom from one element to a different one. • University lecture with G counter • Spitting out the extra

  9. Radioactive Decay • Elements that decay do so regularly • Carbon-14: 5715years • Thorium-230: 75,000 years • Potassium-40: 1,300,000 years • Uranium-238: 4,500,000 yrs

  10. Half Life: The amount of time it takes for half the element in a thing to decay. • Carbon-14

  11. Example Half Life Problem: • I found a fossil! It’s the skull of a weird animal. I took it to a lab and they said it had 1/16th of the carbon left. How old is it? • What element am I using? Carbon-14 • What is its half life? 5715 years • What fraction is left? 1/16th • How many half lives have past? 4 • Go to chart and figure out how many half lives have past. • Multiply the elements half life (that you look up) with the number of half lives that have occurred? • 5715 X 4 = 22860years old

  12. Back to the History of Earth • Early Atmosphere composed of ammonia NH4, Hydrogen H2, Water Vapor H2O, and methane CH4 • Since the Earth was still very hot from the friction caused by rocks hitting it, the temperature would have been above the boiling point of water • Alexander Oparin 1923 said this but NEVER TESTED IT! • Stanley Miller and Harold Urey DID test it in 1953 and found that using electricity (like lightning) would make amino acids and simple pieces of DNA

  13. Miller and Urey Apparatus

  14. History of Earth • Its also possible that some organic compounds came from “Aliens” or meteorites hitting the Earth • These compounds could clump together and form microspheres and coaccervates • Microspheres and coaccervates have the ability to absorb materials from around them and split into smaller ones. • If DNA or RNA got trapped in these and helped it to do better than others without the DNA, primitive life has begun.

  15. Life • In order to be considered living, an organism needs to pass on their traits – through DNA or RNA • Simplest Life forms are archaebacteria • Prokaryotic – no nucleus • Heterotrophic – can not make their own food • Anaerobic – do not use oxygen • Eventually all the ‘food’ would be eaten so how will they survive? EVOLUTION

  16. Evolution occurs when organisms with certain characteristics do better then others; do better means have more babies, which means they pass on more genes.

  17. Think about it • Giraffes feed on trees. If a giraffe has the genes that say ‘be short’ will it survive? Will it make babies? Will the gene that says ‘be short’ survive? • Can a giraffe stretch out his neck and make it stay that way? Maybe. Can that giraffe pass that on to his kids? NO WAY • What if that short giraffe started eating apples found on the ground? Would he survive? Would being short be helpful? Would those genes be passed on? NEW SPECIES • Does that new species have anything to do with the old one?

  18. Review! Test Tomorrow • Where does life come from? • Other living things • BIOGENISIS • What did people used to think life cam from? • Came out of the mud or swamp gases • SPONTANEOUS GENERATION • What did Frank Redi do? • Tried to disprove Spontaneous generation with fly experiment • Made ‘new’ spontaneous generation • What did L. Spallinzanni do? • Tried to disprove Spontaneous generation with broth and sealed flasks but created a ‘VITAL FORCE” argument

  19. Who finally disproved spontaneous generation? • Louis Pasteur • S-neck flask • How old is Earth? • 4.6 billion years • How do we know? • Radioactive dating of isotopes • What is an isotope? • An atom with too much stuff packed in • What is radioactivity? • When the stuff comes flying out and changes into something else • What is the half life of an element? • The time it takes for ½ of the element in a sample to decay

  20. What is decay? • Spit out the extra • Where do I find half lives? • Have to look it up • If 1/16th of an element remains, how many half lives have past? • 4 • If 1/16th of carbon remains in a sample how old is it? • 4 x 5730 = 22,920 • If I have a sample of carbon-14 that is 10g and let it sit for 5730 years, how much mass of carbon-14 will be left? • 5 grams

  21. What was the early earth’s atmosphere made of? • CO2, H2O, NH4, CH4 • What was the temperature of the early earth? • Over boiling • Who figured these particles were in the atmosphere? • Oparin • Who tested this hypothesis? • Miller and Urey • What did Miller and Urey find? • The beginnings of more complex molecules • Coaccervates and microspheres • Where else could these compounds have come from? • Meteorites

  22. How did the first life eat? • Heterotrophic • What did the first life look like? • Simple, no nucleus, or organelles, prokaryotic • Did they use Oxygen? • None there yet • Once all the food was gone what happened next? • The organisms who could make their own food did better and evolved • What is evolution? • Making the most babies and passing on your genes.

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